<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>JavaScript 初体验</title>
</head>
<body>
  <!-- 编写 script 标签 -->
  <script>
    // hello world   注释
    //网页弹框
    alert('Hello JavaScript');

    //控制台输出
    console.log('Hello JavaScript');
  </script>
</body>
</html>